MODBUS LITE V5.01 parameter specification

Table Of Contents
MODBUS parameters "ebm-papst series 84 / 112 / 150 / 200"
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DocNo.: 634505DocNo.: 446144DocNo.:358982DocNo.:322523DocNo.:309753DocNo.:303997DocNo.:276241DocNo.:256078DocNo.:196392 ·Template: 2 dated 6 October 2003 ·File: ext001157859.doc ·Last printed 10/03/2015 15:13:00
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Form 1003
1 Frame protocol
Data are transferred using the MODBUS protocol defined in these specifications
exclusively in an environment defined as a master/slave system. The orderly progression of data is defined by
the master. A slave is required to respond to its command prompt. For this reason, it is important to ensure
that no slave address is assigned more than once when constructing a system.
A twisted pair wire with RS485 standard should preferably be used.
Only RTU transmission mode is supported (see MODBUS over Serial Line Specification & Implementation
guide V1.0, chapter 2.5.1)
ASCII transmission mode is not supported!
1.1 Structure of a byte
According to the MODBUS over Serial Line Specification & Implementation guide V1.0. a byte has the
following structure:
Bit 0
(LSB)
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
(MSB)
Parity
Stop
(high)
The definition of the parity bit ("Even", "Odd", "None") can be set with the parameter "Parity configuration"
(see 2.32.2).
The transmission rate is variable and can be set with the "transmission rate" parameter (see 2.32.1).
1.2 Communication process
The MODBUS over Serial Line Specification & Implementation guide V1.0 defines the following framework for
the transmission protocol:
Command from
master:
Response from fan:
Address
8 bits
Command
8 bits
Data
N * 8 bits
CRC H
8 bits
CRC L
8 bits
Start
> 3.5 char
Address
8 bits
Command
8 bits
Data
N * 8 bits
CRC H
8 bits
CRC L
8 bits
Start
> 3.5 char
In contrast to the general specifications, the maximum telegram length is 23 bytes!